Dried lake beds, failed crops, flattened trees: when we think of global warming we often think of the impacts of droughts and extreme weather. While there is truth in this image, a rather different picture is emerging.
In a paper published in Nature Climate Change, we show that the Earth has been getting greener over the past 30 years. As much as half of all vegetated land is greener today, and remarkably, only 4 percent of land has become browner.
Our research shows this change has been driven by human activities, particularly the rising concentration of carbon dioxide (CO₂) in the atmosphere. This is perhaps the strongest evidence yet of how people have become a major force in the Earth’s functioning.
We are indeed in a new age, the Anthropocene.
How Do You Measure Green?
Plants play a vital role in maintaining Earth as a habitable place, not least through absorbing CO₂. We wanted to know how people are affecting this ability.
To do this, we needed to know how much plants are growing. We couldn’t possibly measure all the plants on Earth so we used satellites observations to measure light reflected and absorbed from the Earth’s surface. This is a good indicator of leaf area, and therefore how plants are growing.
We found consistent trends in greening across Australia, central Africa, the Amazon Basin, southeast United States, and Europe. We found browning trends in northwest North America and central South America.
